Arkansas Dicamba use Regulations for 2021

by Tom Barber, Extension Weed Scientist - February 22, 2021

I have had several conversations with county agents, consultants, and growers over the last couple of weeks about what changes, if any, were made to the Arkansas State Plant Board dicamba use regulations for the 2021 season. The Arkansas State Plant Board met last December to discuss and vote on potential changes for dicamba application, specifically the May 25th cutoff date. No changes were voted successfully in the meeting and at this time (February, 19th) nothing has changed in terms of dicamba use regulations in Arkansas. Currently, the regulations found on the Arkansas State Plant Board Website (found here) state the following:

“From May 26^th through October 31^st of each year, applications of products labeled for agriculture use that contain dicamba are prohibited except for applications made:
a. For turf, ornamental, direct injection for forestry activities and home use are allowed year around.
b. For pasture and range land are allowed year round. However, such applications must maintain buffers required in Section 2 (see section 2 on the plant board website link above); or
c. Pursuant to a special permit for Arkansas land east of the Mississippi river levee may be allowed if all of the following requirements are met. In no event will a special permit be issued for applications made more than 45 days (soybeans) or 60 days (cotton) after planting.
From April 16 through May 25^th all applications for in crop agriculture use:
a. Must maintain a one (1) mile buffer, in all directions, from University and USDA research stations, certified organic crops, and commercially grown specialty crops (defined as a minimum of 1,000 plants or the average annual crop sales for the previous three years exceeding $25,000)
b. Are prohibited from using tank mixes of products containing the active ingredient glyphosate mixed with pesticides containing the active ingredient dicamba labeled for crop use.
c. During application a ½ mile buffer zone in all directions from non dicamba-tolerant crops must be maintained
From April 16^th through October 31, applications of pesticides labeled for agricultural use that contain the active ingredient dicamba are prohibited for pre-plant burndown applications except for:
a. From April 16^th through May 25^th, pesticides labeled for in crop agricultural use, by ground that contain the active ingredient dicamba and allow for the pre-plant (burndown) applications may be applied. However, such applications must maintain the requirements of buffers required in Section B 2 of the regulation guidebook

The federal label for Engenia and Xtendimax were renewed in October 2020 for applications to Xtend and XtendFlex (dicamba tolerant) crops. In this renewal, other uses such as applications in corn, grain sorghum or for burndown prior to planting crops other than Xtend were not included on the revised labels. Therefore the only “labeled” uses allowed for these two herbicides are applications made prior-to or following planting of Xtend/XtendFlex-traited crops. This change in the labelling has resulted in several asking what they can use in place of these products for burndown applications and if there are any alternative dicamba formulations legal in corn or grain sorghum crops.

Based on the Arkansas State Plant Board rules mentioned earlier, any labeled dicamba product can be used for controlling winter weeds up until April 15^th. From April 15^th-May 25^th, dicamba products that are labeled for agriculture use either in pre-plant burndown applications or in corn or grain sorghum crops can be used as long as they are labeled for the use and all previously mentioned buffer restrictions are followed. This includes dicamba herbicide formulations such as Status that are labeled for use in corn. Therefore, dicamba alternatives other than Engenia and Xtendimax will be legal to use for pre-plant burndown and weed control in corn or grain sorghum through May 25^th as long as the product used is labeled for that use and buffers are adhered to.

Engenia and Xtendimax are registered for use in dicamba-tolerant soybean and cotton in Arkansas from burndown through May 25^th or until soybean plants reach R1, whichever occurs first. Tavium can be applied from burndown through V4 or within 45 days after planting or prior to the May 25^th cutoff date, whichever occurs first. Keep in mind all buffer restrictions and application parameters still apply.

Another popular question is: What can I use as a tank-mix alternative to glyphosate (Roundup) for grass control with dicamba applications after April 15? Products containing clethodim (Select) or paraquat (Gramoxone) will have some activity on grasses when tank-mixed with dicamba in a pre-plant burndown situation. Applicators should check for allowable tank-mix partners on Engenia, Tavium and Xtendimax websites for tank-mixes with those products. If the dicamba-tolerant crop is emerged, herbicides containing clethodim or other Group 1 ACCase herbicide can be tank-mixed with dicamba for effective grass control in cotton and soybean as long as it is on the approved tank-mix list. However, some antagonism may occur resulting in reduced grass control, especially if grass weeds are starting to tiller or are larger. The best alternative to achieve the greatest weed control is to make two separate applications. Glyphosate should be applied approximately 5 days before or after the dicamba application.

Training will be required to make any dicamba applications this season. The University of Arkansas System Division of Agriculture has developed a general dicamba use training module that can be found by clicking here. Producers and applicators may be required to take two dicamba trainings depending on anticipated uses. The next to last training listed is for those producers who plan to use dicamba in their pre-plant burndown, corn or grain sorghum crops, or any other non dicamba-tolerant crop application. The last training listed includes links to dicamba manufacturer trainings that cover applications of approved dicamba formulations in Xtend/XtendFlex crops. If producers/applicators plan on applying dicamba during burndown and in-season on Xtend/XtendFlex crops, both trainings are required. Other trainings are available on the website as well, including restricted use pesticide applicator training and a link to the online paraquat training, which is required for purchase, storage, handling and applications of any herbicide containing the active ingredient paraquat.

The dicamba restrictions mentioned above are in addition to the restrictions on the Federal Label for any dicamba product. Producers or applicators should read all labels prior to making a pesticide application. In the case of dicamba this becomes even more important as there are several other restrictions to follow that are not included in this write-up. Labels for Engenia, Tavium and Xtendimax include detailed rules for spraying conditions, nozzle selection, wind and sprayer speeds, boom height, allowable tank-mixtures and in-field spray buffers to sensitive areas. In addition, a volatility reducing agent (VRA) is required for all dicamba applications to dicamba-tolerant crops in 2021.